LONDON (Reuters) - In a sport dominated by giants, Kobe Bryant fears a lack of height could be the downfall of the United States as they bid to retain their Olympic basketball title at the London Games.

The U.S. won their third straight warm-up match on Thursday, beating Britain 118-78 in Manchester, and will now jet off to Barcelona to face Spain and Argentina.

They are clear favorites to win gold in London, but they are not unbeatable, according to Bryant.

"We definitely have weaknesses that teams can take advantage of," he told reporters. "So, we'll get a good look at that.

"It's size. It's size and teams being able to slow the game down and work the ball inside on us, and we have to do a good job of taking care of our defensive pressure."

Head coach Mike Krzyzewski said they are taking nothing for granted, but are confident they can turn their current form into gold medal success.

"We're not going to look great all the time because the rest of the world is that good," he said.

"We're not going to assume anything. Hopefully the way we're playing will translate into a gold medal."

The U.S. begin their Olympic competition against France on July 29.